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phunix/servers/rs/manager.c
Jorrit Herder 78f20c3959 Rest ...
2005-10-21 13:46:47 +00:00

455 lines
16 KiB
C
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/*
* Changes:
* Jul 22, 2005: Created (Jorrit N. Herder)
*/
#include "inc.h"
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <minix/dmap.h>
/* Allocate variables. */
struct rproc rproc[NR_SYS_PROCS]; /* system process table */
struct rproc *rproc_ptr[NR_PROCS]; /* mapping for fast access */
int nr_in_use; /* number of services */
extern int errno; /* error status */
/* Prototypes for internal functions that do the hard work. */
FORWARD _PROTOTYPE( int start_service, (struct rproc *rp) );
FORWARD _PROTOTYPE( int stop_service, (struct rproc *rp,int how) );
PRIVATE int shutting_down = FALSE;
#define EXEC_FAILED 49 /* recognizable status */
/*===========================================================================*
* do_up *
*===========================================================================*/
PUBLIC int do_up(m_ptr)
message *m_ptr; /* request message pointer */
{
/* A request was made to start a new system service. Dismember the request
* message and gather all information needed to start the service. Starting
* is done by a helper routine.
*/
register struct rproc *rp; /* system process table */
int slot_nr; /* local table entry */
int arg_count; /* number of arguments */
char *cmd_ptr; /* parse command string */
enum dev_style dev_style; /* device style */
int s; /* status variable */
/* See if there is a free entry in the table with system processes. */
if (nr_in_use >= NR_SYS_PROCS) return(EAGAIN);
for (slot_nr = 0; slot_nr < NR_SYS_PROCS; slot_nr++) {
rp = &rproc[slot_nr]; /* get pointer to slot */
if (! rp->r_flags & RS_IN_USE) /* check if available */
break;
}
nr_in_use ++; /* update administration */
/* Obtain command name and parameters. This is a space-separated string
* that looks like "/sbin/service arg1 arg2 ...". Arguments are optional.
*/
if (m_ptr->RS_CMD_LEN > MAX_COMMAND_LEN) return(E2BIG);
if (OK!=(s=sys_datacopy(m_ptr->m_source, (vir_bytes) m_ptr->RS_CMD_ADDR,
SELF, (vir_bytes) rp->r_cmd, m_ptr->RS_CMD_LEN))) return(s);
rp->r_cmd[m_ptr->RS_CMD_LEN] = '\0'; /* ensure it is terminated */
if (rp->r_cmd[0] != '/') return(EINVAL); /* insist on absolute path */
/* Build argument vector to be passed to execute call. The format of the
* arguments vector is: path, arguments, NULL.
*/
arg_count = 0; /* initialize arg count */
rp->r_argv[arg_count++] = rp->r_cmd; /* start with path */
cmd_ptr = rp->r_cmd; /* do some parsing */
while(*cmd_ptr != '\0') { /* stop at end of string */
if (*cmd_ptr == ' ') { /* next argument */
*cmd_ptr = '\0'; /* terminate previous */
while (*++cmd_ptr == ' ') ; /* skip spaces */
if (*cmd_ptr == '\0') break; /* no arg following */
if (arg_count>MAX_NR_ARGS+1) break; /* arg vector full */
rp->r_argv[arg_count++] = cmd_ptr; /* add to arg vector */
}
cmd_ptr ++; /* continue parsing */
}
rp->r_argv[arg_count] = NULL; /* end with NULL pointer */
rp->r_argc = arg_count;
/* Initialize some fields. */
rp->r_period = m_ptr->RS_PERIOD;
rp->r_dev_nr = m_ptr->RS_DEV_MAJOR;
rp->r_dev_style = STYLE_DEV;
rp->r_restarts = -1; /* will be incremented */
/* All information was gathered. Now try to start the system service. */
return(start_service(rp));
}
/*===========================================================================*
* do_down *
*===========================================================================*/
PUBLIC int do_down(message *m_ptr)
{
register struct rproc *rp;
pid_t pid = (pid_t) m_ptr->RS_PID;
for (rp=BEG_RPROC_ADDR; rp<END_RPROC_ADDR; rp++) {
if (rp->r_flags & RS_IN_USE && rp->r_pid == pid) {
#if VERBOSE
printf("stopping %d (%d)\n", pid, m_ptr->RS_PID);
#endif
stop_service(rp,RS_EXITING);
return(OK);
}
}
#if VERBOSE
printf("not found %d (%d)\n", pid, m_ptr->RS_PID);
#endif
return(ESRCH);
}
/*===========================================================================*
* do_refresh *
*===========================================================================*/
PUBLIC int do_refresh(message *m_ptr)
{
register struct rproc *rp;
pid_t pid = (pid_t) m_ptr->RS_PID;
for (rp=BEG_RPROC_ADDR; rp<END_RPROC_ADDR; rp++) {
if (rp->r_flags & RS_IN_USE && rp->r_pid == pid) {
#if VERBOSE
printf("refreshing %d (%d)\n", pid, m_ptr->RS_PID);
#endif
stop_service(rp,RS_REFRESHING);
return(OK);
}
}
#if VERBOSE
printf("not found %d (%d)\n", pid, m_ptr->RS_PID);
#endif
return(ESRCH);
}
/*===========================================================================*
* do_rescue *
*===========================================================================*/
PUBLIC int do_rescue(message *m_ptr)
{
char rescue_dir[MAX_RESCUE_DIR_LEN];
int s;
/* Copy rescue directory from user. */
if (m_ptr->RS_CMD_LEN > MAX_RESCUE_DIR_LEN) return(E2BIG);
if (OK!=(s=sys_datacopy(m_ptr->m_source, (vir_bytes) m_ptr->RS_CMD_ADDR,
SELF, (vir_bytes) rescue_dir, m_ptr->RS_CMD_LEN))) return(s);
rescue_dir[m_ptr->RS_CMD_LEN] = '\0'; /* ensure it is terminated */
if (rescue_dir[0] != '/') return(EINVAL); /* insist on absolute path */
/* Change RS' directory to the rescue directory. Provided that the needed
* binaries are in the rescue dir, this makes recovery possible even if the
* (root) file system is no longer available, because no directory lookups
* are required. Thus if an absolute path fails, we can try to strip the
* path an see if the command is in the rescue dir.
*/
if (chdir(rescue_dir) != 0) return(errno);
return(OK);
}
/*===========================================================================*
* do_shutdown *
*===========================================================================*/
PUBLIC int do_shutdown(message *m_ptr)
{
/* Set flag so that RS server knows services shouldn't be restarted. */
shutting_down = TRUE;
return(OK);
}
/*===========================================================================*
* do_exit *
*===========================================================================*/
PUBLIC void do_exit(message *m_ptr)
{
register struct rproc *rp;
pid_t exit_pid;
int exit_status;
#if VERBOSE
printf("RS: got SIGCHLD signal, doing wait to get exited child.\n");
#endif
/* See which child exited and what the exit status is. This is done in a
* loop because multiple childs may have exited, all reported by one
* SIGCHLD signal. The WNOHANG options is used to prevent blocking if,
* somehow, no exited child can be found.
*/
while ( (exit_pid = waitpid(-1, &exit_status, WNOHANG)) != 0 ) {
#if VERBOSE
printf("RS: proc %d, pid %d, ", rp->r_proc_nr, exit_pid);
if (WIFSIGNALED(exit_status)) {
printf("killed, signal number %d\n", WTERMSIG(exit_status));
}
else if (WIFEXITED(exit_status)) {
printf("normal exit, status %d\n", WEXITSTATUS(exit_status));
}
#endif
/* Search the system process table to see who exited.
* This should always succeed.
*/
for (rp=BEG_RPROC_ADDR; rp<END_RPROC_ADDR; rp++) {
if ((rp->r_flags & RS_IN_USE) && rp->r_pid == exit_pid) {
rproc_ptr[rp->r_proc_nr] = NULL; /* invalidate */
if ((rp->r_flags & RS_EXITING) || shutting_down) {
rp->r_flags = 0; /* release slot */
rproc_ptr[rp->r_proc_nr] = NULL;
}
else if(rp->r_flags & RS_REFRESHING) {
rp->r_restarts = -1; /* reset counter */
start_service(rp); /* direct restart */
}
else if (WIFEXITED(exit_status) &&
WEXITSTATUS(exit_status) == EXEC_FAILED) {
rp->r_flags = 0; /* release slot */
}
else {
#if VERBOSE
printf("Unexpected exit. Restarting %s\n", rp->r_cmd);
#endif
/* Determine what to do. If this is the first unexpected
* exit, immediately restart this service. Otherwise use
* a binary exponetial backoff.
*/
if (rp->r_restarts > 0) {
rp->r_backoff = 1 << MIN(rp->r_restarts,(BACKOFF_BITS-1));
rp->r_backoff = MIN(rp->r_backoff,MAX_BACKOFF);
}
else {
start_service(rp); /* direct restart */
}
}
break;
}
}
}
}
/*===========================================================================*
* do_period *
*===========================================================================*/
PUBLIC void do_period(m_ptr)
message *m_ptr;
{
register struct rproc *rp;
clock_t now = m_ptr->NOTIFY_TIMESTAMP;
int s;
/* Search system services table. Only check slots that are in use. */
for (rp=BEG_RPROC_ADDR; rp<END_RPROC_ADDR; rp++) {
if (rp->r_flags & RS_IN_USE) {
/* If the service is to be revived (because it repeatedly exited,
* and was not directly restarted), the binary backoff field is
* greater than zero.
*/
if (rp->r_backoff > 0) {
rp->r_backoff -= 1;
if (rp->r_backoff == 0) {
start_service(rp);
}
}
/* If the service was signaled with a SIGTERM and fails to respond,
* kill the system service with a SIGKILL signal.
*/
else if (rp->r_stop_tm > 0 && now - rp->r_stop_tm > 2*RS_DELTA_T
&& rp->r_pid > 0) {
kill(rp->r_pid, SIGKILL); /* terminate */
}
/* There seems to be no special conditions. If the service has a
* period assigned check its status.
*/
else if (rp->r_period > 0) {
/* Check if an answer to a status request is still pending. If
* the driver didn't respond within time, kill it to simulate
* a crash. The failure will be detected and the service will
* be restarted automatically.
*/
if (rp->r_alive_tm < rp->r_check_tm) {
if (now - rp->r_alive_tm > 2*rp->r_period &&
rp->r_pid > 0) {
#if VERBOSE
printf("RS: service %d reported late\n", rp->r_proc_nr);
#endif
kill(rp->r_pid, SIGKILL); /* simulate crash */
}
}
/* No answer pending. Check if a period expired since the last
* check and, if so request the system service's status.
*/
else if (now - rp->r_check_tm > rp->r_period) {
#if VERBOSE
printf("RS: status request sent to %d\n", rp->r_proc_nr);
#endif
notify(rp->r_proc_nr); /* request status */
rp->r_check_tm = now; /* mark time */
}
}
}
}
/* Reschedule a synchronous alarm for the next period. */
if (OK != (s=sys_setalarm(RS_DELTA_T, 0)))
panic("RS", "couldn't set alarm", s);
}
/*===========================================================================*
* start_service *
*===========================================================================*/
PRIVATE int start_service(rp)
struct rproc *rp;
{
/* Try to execute the given system service. Fork a new process. The child
* process will be inhibited from running by the NO_PRIV flag. Only let the
* child run once its privileges have been set by the parent.
*/
int child_proc_nr; /* child process slot */
pid_t child_pid; /* child's process id */
char *file_only;
int s;
message m;
/* Now fork and branch for parent and child process (and check for error). */
child_pid = fork();
switch(child_pid) { /* see fork(2) */
case -1: /* fork failed */
report("RS", "warning, fork() failed", errno); /* shouldn't happen */
return(errno); /* return error */
case 0: /* child process */
/* Try to execute the binary that has an absolute path. If this fails,
* e.g., because the root file system cannot be read, try to strip of
* the path, and see if the command is in RS' current working dir.
*/
execve(rp->r_argv[0], rp->r_argv, NULL); /* POSIX execute */
file_only = strrchr(rp->r_argv[0], '/') + 1;
execve(file_only, rp->r_argv, NULL); /* POSIX execute */
printf("RS: exec failed for %s: %d\n", rp->r_argv[0], errno);
exit(EXEC_FAILED); /* terminate child */
default: /* parent process */
child_proc_nr = getnprocnr(child_pid); /* get child slot */
break; /* continue below */
}
/* Only the parent process (the RS server) gets to this point. The child
* is still inhibited from running because it's privilege structure is
* not yet set. First try to set the device driver mapping at the FS.
*/
if (rp->r_dev_nr > 0) { /* set driver map */
if ((s=mapdriver(child_proc_nr, rp->r_dev_nr, rp->r_dev_style)) < 0) {
report("RS", "couldn't map driver", errno);
if(child_pid > 0) kill(child_pid, SIGKILL); /* kill driver */
else report("RS", "didn't kill pid", child_pid);
rp->r_flags |= RS_EXITING; /* expect exit */
return(s); /* return error */
}
}
/* The device driver mapping has been set, or the service was not a driver.
* Now, set the privilege structure for the child process to let is run.
* This should succeed: we tested number in use above.
*/
m.PR_PROC_NR = child_proc_nr;
if ((s = _taskcall(SYSTEM, SYS_PRIVCTL, &m)) < 0) { /* set privileges */
report("RS","call to SYSTEM failed", s); /* to let child run */
if(child_pid > 0) kill(child_pid, SIGKILL); /* kill driver */
else report("RS", "didn't kill pid", child_pid);
rp->r_flags |= RS_EXITING; /* expect exit */
return(s); /* return error */
}
#if VERBOSE
printf("RS: started '%s', major %d, pid %d, proc_nr %d\n",
rp->r_cmd, rp->r_dev_nr, child_pid, child_proc_nr);
#endif
/* The system service now has been successfully started. Update the rest
* of the system process table that is maintain by the RS server. The only
* thing that can go wrong now, is that execution fails at the child. If
* that's the case, the child will exit.
*/
rp->r_flags = RS_IN_USE; /* mark slot in use */
rp->r_restarts += 1; /* raise nr of restarts */
rp->r_proc_nr = child_proc_nr; /* set child details */
rp->r_pid = child_pid;
rp->r_check_tm = 0; /* not check yet */
getuptime(&rp->r_alive_tm); /* currently alive */
rp->r_stop_tm = 0; /* not exiting yet */
rproc_ptr[child_proc_nr] = rp; /* mapping for fast access */
return(OK);
}
/*===========================================================================*
* stop_service *
*===========================================================================*/
PRIVATE int stop_service(rp,how)
struct rproc *rp;
int how;
{
/* Try to stop the system service. First send a SIGTERM signal to ask the
* system service to terminate. If the service didn't install a signal
* handler, it will be killed. If it did and ignores the signal, we'll
* find out because we record the time here and send a SIGKILL.
*/
#if VERBOSE
printf("RS tries to stop %s (pid %d)\n", rp->r_cmd, rp->r_pid);
#endif
rp->r_flags |= how; /* what to on exit? */
if(rp->r_pid > 0) kill(rp->r_pid, SIGTERM); /* first try friendly */
else report("RS", "didn't kill pid", rp->r_pid);
getuptime(&rp->r_stop_tm); /* record current time */
}
/*===========================================================================*
* do_getsysinfo *
*===========================================================================*/
PUBLIC int do_getsysinfo(m_ptr)
message *m_ptr;
{
vir_bytes src_addr, dst_addr;
int dst_proc;
size_t len;
int s;
switch(m_ptr->m1_i1) {
case SI_PROC_TAB:
src_addr = (vir_bytes) rproc;
len = sizeof(struct rproc) * NR_SYS_PROCS;
break;
default:
return(EINVAL);
}
dst_proc = m_ptr->m_source;
dst_addr = (vir_bytes) m_ptr->m1_p1;
if (OK != (s=sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len)))
return(s);
return(OK);
}
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